The invention discloses a branch controllable titanium dioxide nanotube array thin film and a preparation method thereof. The thin film consists of an array of a titanium dioxide nanotube formed by connecting a main tube and a branch tube in series; the thickness of the thin film is 1-100mum, and the porosity factor is 40-60 percent. The preparation method comprises the following steps: preparinga main tube electrolyte according to the proportion that the mole ratio of ammonium fluoride to glycol to water is 0.05-0.15:17.7:0.015-0.025, and preparing a branch tube electrolyte according to theproportion that the mole ratio of hydrofluoric acid to glycol is 0.15-0.25:17.7; then firstly, putting one surface of a titanium sheet in the main tube electrolyte to serve as the anode; carrying outanode oxidization under the conditions that the DC voltage is 55-65V and the temperature is 0-35 DEG C for 0.5-6h; then using the glycol to clean the anode; subsequently, putting the surface which isanodized in the branch tube electrolyte to serve as the anode, and carrying out anode oxidization under the conditions that the DC voltage is 30-120V and the temperature is 0-35 DEG C for more than 30min, thereby preparing the thin film. The thin film can be widely used for fields of dye-sensitized solar cells, gas sensors, photolytic water hydrogen production and photonic crystal.